181313RevisionRevision19191515171715+15=46+24=52+28=30708031+9=4018+72=9027+23=14+46=5060numbernumberssDo the mathDo the mathStudy the new works.Study the new works.numbernumber数字数字thirtythirty三十三十sixtysixty六十六十fiftyfifty五十五十eightyeighty八十八十fortyforty四十四十seventyseventy七十七十ninetyninety九十九...
